Rotary cultivator



United States Patent 1 Inventor q srisil-Mq r 1218 Hammond Ave., NewWestminster, B it s fiflvm a w sia no. [21] Appl. No. 723,822 [22] FiledApril 24, 1968 [45] Patented Sept. 29, I970 [54] ROTARY CULTIVATOR 9Claims, 4 Drawing Figs.

[52] 0.8. CI 172/96, 172/265: 172/544: 172/706 51 Int. Cl A0lb 33/00[50] Field olSearch l72/95,96, 117, 264, 265, 269, 270, 543, 544,545,706, 705; 16/141,144, 182

[56] References Cited UNITED STATES PATENTS 790,410 5/1905 Warnel72/269X 1,050,923 1/1913 DeViese l72/96X Primary Examiner- Robert E.Pulfrey Assistant Examiner-James W. Peterson Anornvy- Fcthcrstonhaughand (To.

ABSTRACT: A rotary cultivator having a rotable driven member upon whicha digging tool is rotatably journalled for rotation about an axisparallel to but off-center relative to the axis of the member forswinging movement between an extended position and a retracted position.A follower is slidably mounted on the tool and is spring-urged radiallyinwardly against a cam which moves the follower radially outwardlyagainst a spring as the tool is moved from its extended to its retractedposition. The cam is convexly curved so that the effective resistance ofthe spring to the rotation of the tool diminishes as the tool is movedaway from its extended posi- [1011.

Patented Sept. 29, 1970 I 3,530,946

' MEDERgC .J. MAJOR Wa d? ATTORNEYS ROTARY CULTIVATOR BACKGIIOUND OF THEINVENTION This invention relates to cultivators and particularlycultivators of the rotary type wherein a plurality of digging tools arerotated consecutively into engagement with the ground surface to betilled as the cultivator is moved.

This type of cultivator is constructed so that the digging tools, uponencountering an immovable ground obstruction such as a heavy stone, willretract to clear the latter so as not to damage the cultivator and afterhaving cleared, will automatically return to an extended operatingposition. The digging tools and their operating mechanism have usuallyin cluded a spring which continually urges the tools to their extendedposition and which will give to permit the tools to rotate to retractedpositions upon encountering an immovable object. In order to provide forretractive movement of the teeth against their springs, many cultivatorshave been provided with specially designed linkage which will increasethe mechanical advantage of the teeth against their springs as the teethmove from their extended position whereby the re sistance to rotation ofthe teeth diminishes as they are moved to their retracted positions.

Cultivators of prior art utilizing linkages of this nature have beenconstructed so that the linkages are exposed to earth, rocks and otherdebris and the moving parts thereof have been subject to wear andjamming. Furthermore, prior art cultivators employing this linkage havebeen relatively costly to build and difficult to maintain and adjust.

SUMMARY OF THE INVENTION The present invention provides a rotarycultivator of the last-mentioned type in which the linkage or mechanismoperating the tool is completely enclosed within the tool itself and istherefore fully protected from damage or derangement by debris thrown upby the cultivator. I

The cultivator of the present invention, furthermore, is strong yet hasvery few working parts and is therefore relatively cheap to manufactureand maintain and adjust.

The operating mechanism of the present invention is also arranged toprovide high'initial resistance of the digging tools to movement out oftheir retracted positions and thereafter permit easy yielded movement ofthe tools to their retracted positions.

The present invention comprises a driven member rotatable about ahorizontal axis, a radially elongated diggingtool mounted at, one endon, the driven member for swinging movement about an axis parallel tothe rotational axis of the latter between a radially extended positionand a retracted position, a cam follower slidably mounted on the diggingtool for radial movement relative thereto, resilient means reactingagainst the tool and follower for yieldably resisting radially outwardmovement of the latter, and a cam having a camming surface against whichthe follower slidably bears for moving the latter radially'outwardlyagainst the action of the resilient means when the tool is swung fromits extended to its retracted position, said camming surface extendingas a con- -vex:curve so that the effective resistance of the resilientmeans to rotational movement of the tool diminishes as the tool movesaway from its extended position.

BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a side view of part of thecultivator showing the rotatable member and digging tools thereon,

FIG. 2 is an enlarged side view, partially in section, of a diggingtoolin its radially extending position,

1 FIG. 3 is a view similar to FIG. 2 illustrating partially, a diggingtool in a retracted position, and

FIG. 4is a sectional view taken along line 4-4 of FIG. 2.

2 DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus hereindisclosed is particularly designed for use on a cultivating machinemovable over a ground surface and having a rotatable, horizontal, powerdriven shaft. As machines of this type are well known, it is notconsidered necessary to describe or show herein the details of itsconstruction, it being sufficient for the purposes of the presentinvention to understand that theshaft is carried by a frame which issupported by ground wheels and is power driven to rotate in the samedirection as the ground wheels.

Referring to the drawings, the numeral designates the power drivenrotatable shaft on which a plurality of discs 11 (one being shown) arenonrotatably mounted as by a key and slot arrangement 12. The cultivatoris normally moved in the direction indicated by the arrow 13 and theshaft is rotated in the direction indicated by the arrow l4. Rotatablymounted on laterally extending bosses l5 nonrotatably secured to thedisc 11, which is a relatively thick steel plate, are digging tools 16(four being shown) which, under the influence of centrifugal forces asthe disc 11 is rotated and under the action of operating mechanism,hereinafter to be described, normally assume an extended position asshown in solid lines in FIG. 1 and when striking an immovable objectrotate towards a retracted position as shown in dotted lines in thelatter FIG.

Referring to FIGS. 2 and 4, one of the bosses 15 and a digging tool 16are shown in detail.

The boss 15 is generally cylindrical in shape and fits at one end 20into an aperture 22 formed in the disc near the peripheral edge of thelatter so as to project laterally therefrom with its longitudinal axis23 normal to the plane of the disc and is welded rigidly to the latteras at 24. The'boss has a short thick cylindrical root section 25extending a short distance outwardly from the disc 11 terminating inannular shoulder 26, said boss being reduced in diameter at said annularshoulder to form an elongated cylindrical spindle 28. This spindle ismachined to provide a flat, centrally located seat extending parallel tothe longitudinal axis 23. This seat terminates short of the shoulder 26so that the spindle 28 has a short cylindrical section 32. The seat 30terminates at its trailing edge in a raised arcuate lip 36. The lip 36eases into a convexially curvate camming surface 37 which casesgradually into the true cylindrical surface of the spindle 28.

The digging tool 16 is formed having an elongated shank 40 having anenlarged annular hub.41 at one end 42 thereof which rotatably fits overthe spindle 28 and slidably and sealably bears against a washer 43fitted against the shoulder 26. The hub 41 is provided with an internalstop 44 for engaging'the seat 30 and is maintained in position on thespindle 28, by means of a retaining cap 45 fitted against the free end27 of the boss and secured in place by means of machine bolts 47extended through the cap into suitably tapped holes 48 in the boss. Thiscap 45 slidably and sealably fits against the hub 41.

At the free or other end 50 of the shank, a pointed digging tooth 51having a tip 52 is detachably secured by means of a nut and bolt typeconnector 53 passed through cooperating apertured flanges 54 and 55formed on the digging tooth and shank respectively.

The shank is provided with an axially and radially extending bore whichterminates at one end 61 in an elongated guide passage 62 of squarecross-section, said guide passage opening out into the hub 41 inconfronting relationship to the seat '30 and camming surface 37.The'bore also opens out of the free end of the shank and is internallythreaded to threadedly receive an externally threaded plug 65 which maybe secured against rotation by means of a set screw 66.

Slidably mounted in the guide passage 62 is a cam follower 70, saidfollower being elongated in a radial direction and having a squarecross-sectional configuration so as to have a tight yetslidable andnonrotatable fit in the guide passage 62. The base 73 of the followerfaces the spindle extending in a plane normal to the axis of the guidepassage and is chamfered at its edges. The follower is also providedwith a longitudinally extending centrally located passage 74 thediameter of which is sufficient to provide easy flow of a lightlubricating grease therethrough. A coiled compression spring 75 locatedin the bore extends under compression between the plug 65 and follower70 urging the latter into slidably engagement with the seat and cammingsurface of the spindle 28.

In order to lubricate the digging tool 16, a passage 78 is drilledthrough the shank to intersect the bore and is provided with agrease-fitting 80. Sufficient light lubricating grease is appliedthrough the grease-fitting 80 to completely fill the bore and, viapassage 74, the space between the hub 41 and spindle 28.

The operation of the digging tool may be best described with referenceto FIGS. 1, 2 and 3.

During a tilling or cultivating operation the centrifugal forces actingon the tool will tend to induce the latter to assume a position in whichits center of gravity is aligned with its axis of rotation and the axisof rotation of the shaft 10. The preferred position of the tool in itsextended position, however, is such that the tip 52 of the tooth isaligned with the aforementioned axes of rotation in that when the toolstarts to move to a retracted position its tip will move inwardlytowards the periphery of the disc 11.

The boss is therefore angularly arranged so that the stop 44 will engagethe seat 30 with the face of the cam follower 70 flush against thelatter to prevent movement of the tooth, under centrifugal force, beyondthe preferred extended position.

The tool will normally assume its extended position when Working. Whenthe tool meets an obstruction sufficiently heavy enough to cause it torotate, the follower will attempt to climb over the lip 36. However, inorder to do this, the follower must move outwardly against the action ofthe compression spring 75. As it is not intended that the tool shallmove from its extended position under ordinary working conditions where,for example, only small stones are encountered, a compression spring ischosen having sufficient strength to permit the follower to climb overthe lip only when the digging tool encounters an object of sufficientweight and size which would lift the entire cultivator if the diggingtool were not able to retract.

The initial resistance to retractive rotation of the digging tool istherefore relativelyhigh, however, once the follower has moved onto thecamming surface 37, the resistance offered by the spring and follower tofurther rotation of the digging tool diminishes as the tool movestowards its retracted position. it will be seen, with reference to FIGS.2 and 3, that due to the curved aspect of the camming surface 37, themechanical advantage of the digging tool against the spring increases asthe tool is rotated towards its retracted position, which, consequentlyresults in a steadily diminishing effective resistance of the spring torotation of the tooth as the latter is moved towards said retractedposition. When the cultivator has moved sufficiently to permit thedigging tool to clear the obstruction, the tool, under the action of thefollower against the camming surface and also under the action ofcentrifugal forces, will immediately return to its extended position.

During the working of the cultivator, stones and roots and the like arethrown upwardly into the air and consequently, are a hazard in that theytend to cause jamming of the operating linkage of conventional diggingtools. in the present invention, as herein described, all the operatingcomponents of the digging tool such as the cam follower and spring, arehidden within the tool itself so that jamming by rocks and the like isimpossible. Furthermore, the working components of the digging tool areprotected from damage due to abrasive materials as the tool is fullysealed by the cap 45 and seal 43. Lubrication of the working components,furthermore, is assured as the cam follower 70 acts in the nature ofapump as it reciprocally moves in the guide passage 62 due to rotationalmovement of the digging tool, thereby forcing the lubricant through thepassage 74.

I claim: 1. Rotary cultivator apparatus comprising a driven memberrotatable about a horizontal axis, a cylindrical boss projectinglaterally from the driven member and offset from the rotational axis ofthe latter and having a camming surface formed thereon, a radiallyelongated digging tool swingably journalled at one end on the boss forrotative movement about an axis parallel to the rotational axis of thedriven member, said tool having a radial bore opening outwardly at oneend to the camming surface and being closed at its other end, a camfollower slidably mounted in the bore for slidably engaging the cammingsurface and movable radially outwardly of the latter as the tool ismoved from its extended position towards its retracted position, acompression spring mounted in the bore between the closed end thereofand the follower for yieldably resisting radial outward movement of thefollower, said camming surface having a sharp rise at the beginning ofthe movement from the extended to the retracted position to give a highresistance to movement of the tool from the extended position.

2. Rotary cultivator apparatus as claimed in claim 1 including a seatformed in the boss extending in a plane normal to the axis of the borefor seating the follower when the tool is in its extended position and araised lip at one edge of the seat forming part of the camming surfaceof the boss, the height of said lift and the length of its cammingsurface being sufficient to permit the follower to move against theaction of the spring only under rotational pressures against the toolexceeding a predetermined value.

3. Rotary cultivator apparatus as claimed in claim 1 including anannular shoulder encircling the boss against which one side of the toolslidably and sealably fits and a cap detachably secured to the free endof the boss having a slidable sealing fit against the other side of thetool so as to maintain the tool on the boss.

4. Rotary cultivator apparatus as claimed in claim 1 including alubricating injection passage formed in the tool intersecting the radialbore, said passage being provided with a lubricating fitting tofacilitate the injection of lubricant into the bore, said cam followerhaving a lubricating passage formed therethrough to permit the passageof lubricant therethrough as the follower moves in the bore.

5. Rotary cultivator apparatus as claimed in claim 1 in which the boreis internally threaded at its end opposite its said one end andincluding a plug having corresponding screw threads engaging the threadsof the bore whereby said plug will be radially adjustable so as topermit compression adjustment of the spring.

6. Rotary cultivator apparatus as claimed in claim 1 in which the drivenmember comprised a disc, the peripheral edge of which is above theground surface to be tilled and the digging tool, in the retractedposition is wholly within the periphery of the disc.

7. Rotary cultivator apparatus as claimed in claim 1 in which thedigging tool comprises an elongated shank having a cylindrical hub atone end for rotatably fitting over the boss and a digging tooldetachably connected to the other end thereof.

8. Rotary cultivator apparatus as claimed in claim 1 in which said oneend of the bore and the follower have a matching non-circularcross-section so as to prohibit rotation of the follower in the bore.

9. Rotary cultivator apparatus as claimed in claim 1 including a stopengagable by the follower when the tool is in its extended position toprevent rotation of the tool in a direction opposite to the directionthat the tool rotates when moving to its retracted position.

